Debian Linux 12 “Bookworm” has been released. As of 23/July/2023, Debian 12.6 point was released on the 29 june 2024. The new version offers updated packages and five years of support. This page provides a step-by-step guide to updating Debian 11 Bullseye to Debian 12 Bookworm using command-line options, including upgrading all installed packages.

The procedure is as follows:

1. Backup the system.
2. Update existing packages and reboot the Debian 11 system.
3. Edit the file /etc/apt/sources.list using a text editor and replace each instance of bullseye with bookworm. Next find the update line, replace keyword bullseye-updates with bookworm-updates. Finally, search the security line, replace keyword bullseye-security with bookworm-security.
4. Update the packages index on Debian Linux, run:

   frater@host:~$ sudo apt update

5. Prepare for the operating system minimal system upgrade, run:

   frater@host:~$ sudo apt upgrade --without-new-pkgs

6. Finally, update Debian 11 to Debian 12 Bookworm by running:

   frater@host:~$ sudo apt full-upgrade

7. Reboot the Linux system so that you can boot into Debian 12 Bookworm
8. Verify that everything is working correctly.

Let us see all commands step by step to upgrade Debian 11 Bullseye to Debian 12 Bookworm safely running in the cloud or bare metal environment.

Backing up all data and system configurations is extremely important. To do this efficiently, cloud-based virtual machines can be quickly backed up and restored using snapshots. Check os version in Linux using the lsb_release command.

frater@host:~$ lsb_release -a
No LSB modules are available.
Distributor ID:	Debian
Description:	Debian GNU/Linux 11 (bullseye)
Release:	11
Codename:	bullseye

Note down the Linux kernel version too. Try the uname command:

frater@host:~$ uname -mrs
Linux 5.10.0-23-amd64 x86_64

Also note down the Debian version using the cat command:

frater@host:~$ cat /etc/debian_version
11.7